1. Field of the Invention
This invention relates to locks and has particular reference to electrically controlled door locks such as those controlled from a remote point or those controlled by a magnetic card or a push button combination in which buttons must be pressed in a predetermined order to effect release of the lock.
2. Description of the Prior Art
Door locks, particularly of the key controlled type,, are generally of a standard size and fit in a standard size opening in a door. Thus, they are usually interchangeable.
On the other hand, electrically controlled locks are of particular advantage in high security situations, hotels, etc., where keys used to open the usual key locks may be readily copied, or the locks may be readily picked, to enable unauthorized access to otherwise secured locations. However, electrically controlled locks, either of the remotely controlled type or the push button combination type, are generally quite bulky and of a larger size, requiring special door lock openings, so that they are not easily interchangeable with key locks. Furthermore, electrically controlled locks generally require relatively large electric power supplies, thus rendering it impractical to provide a self contained lock unit with batteries incorporated therein or on the door, but require instead, electrical power from an external source.
In our copending application, Ser. No. 07/026,307, filed Mar. 16, 1987, we have disclosed and claimed an electrically controlled lock which requires only low powered electrical pulses for operation and thus enables the use of miniature so called AA batteries or the like. This allows the lock unit to be mounted as a self-contained unit on a door. Although such lock unit is very satisfactory and is applicable to many different locking applications, it requires two electromagnetic devices and associated circuitry for operation.